This invention relates to a control device of an automatic transmission for a vehicle. More particularly, it relates to a device for controlling the automatic transmission so as to suit its gearshift operation to a driver's pedalling operation for acceleration and deceleration.
Such a device for controlling the operation of the automatic transmission can be found in Japanese Unexamined Patent Publication No.3-129161. In the publication, when an accelerator pedal is pressed at a high speed, the device operates to shift a downshift change line to a direction of high speed of vehicle. Consequently, the tendency that a gearshift in the automatic transmission is changed to the down side is so increased that the actual downshift change can be matched with the driver's pedalling to the accelerator pedal.
However, in the conventional device as mentioned above, since the tendency of the downshift change is increased in constant ratio, the drivers' estimation of whether the increased tendency is appropriate or not, are different dependent to the drivers. That is, the increased tendency for downshift change is not always acceptable for all type of drivers.
In detail, there are all sorts of drivers including some drivers who like a gentle drive and the other drivers who like an active drive. Although the tendency of the downshift change in the automatic transmission is changed in proportion to the pedalling speed of the driver in the prior art device, the gentle driver may feel that the transmission is subject to change for downshift and the active driver may feel that the transmission is not subject to change for downshift, so far as the relationship between the tendency of the downshift change and the pedalling speed is fixed. In other words, in the prior art device, the gearshift in the automatic transmission cannot be carried out so as to be convenient for all type of drivers.
In addition, even if the same kind of automatic transmissions are installed with vehicles, each potential of acceleration differs with the vehicles equipped with engines of different power, weight and so on. For example, in the vehicle having a low potential of acceleration, since the accelerator pedal of the vehicle is apt to be pressed at a relatively high speed, the tendency of the downshift change would be increased uniformly so that the driver may feel that it is disagreeable.